After you upgrade to vCenter Server appliance, can decommission external Platform Services Controller instances.
After converging an external Platform Services Controller node to a vCenter Server appliance, decommission the original external Platform Services Controller. Decommissioning a Platform Services Controller shuts it down and removes it from the single sign-on domain.
Prerequisites
Make sure no vCenter Server instances are pointing to the Platform Services Controller before decommissioning.
Reconfigure any products deployed into the environment that use the Platform Services Controller to use the newly deployed vCenter Server appliance.
Make a backup of the Platform Services Controller before decommissioning to ensure no loss of data.